Question

I have an Arduino microcontroller listening on COM3. Using the arduino IDE and the Serial monitor works fine to send and receive data.

I would like to send and receive data from Python, but it’s not immediately obvious how to do so. (I’d also be fine doing it in C# if it was substantially easier.)

I found arduino_serial.py, but it only works for Unix. Fortunately, I have a Ubuntu 10.10 VBox set up. However, I have no idea if that VM can access serial ports or if special steps are required to do so.

I also found pySerial, which looks pretty legitimate. However, I’m also unsure how to use it. It wants serial port names. How do I find out what valid values for these are?

For example, pySerial mentions that you can “Open named port at “19200,8,N,1”, 1s timeout” with the following command:

>>> ser = serial.Serial('/dev/ttyS1', 19200, timeout=1)

But I have no idea how you would know that /dev/ttyS1 was a valid port name.

Is there good documentation for getting started on this?

Update: I’m using Ubuntu with arduino_serial, but still having trouble.

This program is running on the Arduino:

void setup() { 
  Serial.begin(9600);
}

void loop() { 
  if (Serial.available()) {
    Serial.print((char)Serial.read());
  }
}

I see that a port called tty0 is available:

foo@bar:~/baz$ dmesg | grep tty
[    0.000000] console [tty0] enabled

I then try to connect with arduino_serial:

foo@bar:~/baz$ sudo python
[sudo] password for foo: 
Python 2.6.6 (r266:84292, Sep 15 2010, 15:52:39) 
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import arduino_serial
>>> sp = arduino_serial.SerialPort("/dev/tty0", 9600)
>>> sp.write("foo")
>>> sp.read_until("\n")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "arduino_serial.py", line 107, in read_until
    n = os.read(self.fd, 1)
OSError: [Errno 11] Resource temporarily unavailable

Why am I getting this error? What am I doing wrong?

Answer 1

I have a project called Yaam on CodePlex that uses C# to send data through the serial port. Check that out for an example. On the C# side (see Yaam\Yaam.xaml.cs), simply use the SerialPort class in the System.IO.Ports namespace. Once you instantiate the object and set the properties (baud rate, com port, etc), simply call.Open() . There are also plenty of other examples on the web. Take a look at these:

• http://jtoee.com/2009/02/talking-to-an-arduino-from-net-c/
• http://www.instructables.com/id/Interfacing-your-arduino-with-a-C-program/